Nasa's hopes of creating a permanently crewed moon base may have taken one giant leap forward with the discovery of water, but scientists still need to decide how to build such a lunar outpost.

One design under consideration draws inspiration from bouncy castles. The "inflatable habitat" would be roomy enough for four astronauts and could be deployed and packed away in 10 minutes. Another design requires astronauts to live in two pressurised containers that sit on eight legs and are connected by an airlock.

The most likely initial moon base would involve astronauts moving pressurised, prefabricated modules on to the surface and connecting them to create a network of rooms, as was done with the International Space Station. In time, lunar rock and dirt could eventually be used to make materials for a more ambitious structure.

A lunar base would give astronauts an unprecedented ability to study the moon and garner more clues about its formation 4.4bn years ago.

A permanent base on the far side of the moon could host instruments to look at the heavens, away from interference from the Earth.

The discovery of water on the moon comes at a critical time for Nasa as the White House is deliberating its direction over the next 20 years. Among the proposals in a major review is a permanent moon base, from which astronauts would explore the terrain and gain expertise required for an eventual mission to Mars.

The review says: "By first exploring the moon, we could develop the operational skills and technology for landing on, launching from and working on a planetary surface. In the process, we could acquire an understanding of human adaptation to another world that would one day allow us to go to Mars. Over many missions, a small colony of habitats would be assembled, and explorers would begin to live there for many months, conducting scientific studies and prospecting for resources that could be used as fuel."

Ian Crawford, a scientist at Birkbeck College in London, said: "These new results come at a time when they could influence the decision. A moon base could be more practical now, because of the easier access to indigenous water."